Re: [Qemu-devel] [PATCH 0/7] tcg: conditional set and move opcodes

[Laurent Desnogues]

On Thu, Dec 17, 2009 at 4:32 PM, malc <address@hidden> wrote:
[...]
>
> Some:
>  a. It breaks tcg on PPC[1]:
>
>    ...qemu/tcg/tcg.c:1378: tcg fatal error

What a surprise :-)

I can provide a similar patch for ARM (I already have one
for my own implementation of setcond), but I'll wait for this
patch series to stabilize first.


Laurent

>  b. Documentation for movcond has a typo, t0 is assigned not t1
>
>  c. Historically things like that were made conditional with
>    a generic fallback (bswap, neg, not, rot, etc)
>
>  d. Documentation for setcond2 is missing
>
>  e. There's some indentation weirdness here and there and `git am'
>    complains about added trailing whitespace
>
> It would also be interesting to learn what impact adding those two
> has on performance, any results?
>
> [..snip..]
>
> [1] With following i can run some i386 user tests on PPC32 (ls,
>    openssl)
>
> diff --git a/tcg/ppc/tcg-target.c b/tcg/ppc/tcg-target.c
> index 07e6941..195af13 100644
> --- a/tcg/ppc/tcg-target.c
> +++ b/tcg/ppc/tcg-target.c
> @@ -316,6 +316,7 @@ static int tcg_target_const_match(tcg_target_long val,
>  #define STH    OPCD(44)
>  #define STW    OPCD(36)
>
> +#define ADDIC  OPCD(12)
>  #define ADDI   OPCD(14)
>  #define ADDIS  OPCD(15)
>  #define ORI    OPCD(24)
> @@ -339,6 +340,7 @@ static int tcg_target_const_match(tcg_target_long val,
>  #define CRANDC XO19(129)
>  #define CRNAND XO19(225)
>  #define CROR   XO19(449)
> +#define CRNOR  XO19( 33)
>
>  #define EXTSB  XO31(954)
>  #define EXTSH  XO31(922)
> @@ -365,6 +367,8 @@ static int tcg_target_const_match(tcg_target_long val,
>  #define MTSPR  XO31(467)
>  #define SRAWI  XO31(824)
>  #define NEG    XO31(104)
> +#define MFCR   XO31( 19)
> +#define CNTLZW XO31( 26)
>
>  #define LBZX   XO31( 87)
>  #define LHZX   XO31(279)
> @@ -1073,6 +1077,95 @@ static void tcg_out_brcond (TCGContext *s, int cond,
>     tcg_out_bc (s, tcg_to_bc[cond], label_index);
>  }
>
> +static void tcg_out_setcond (TCGContext *s, int cond, TCGArg arg0,
> +                             TCGArg arg1, TCGArg arg2, int const_arg2)
> +{
> +    int crop, sh;
> +
> +    switch (cond) {
> +    case TCG_COND_EQ:
> +        if (const_arg2) {
> +            if ((uint16_t) arg2 == arg2) {
> +                tcg_out32 (s, XORI | RS (arg1) | RA (0) | arg2);
> +            }
> +            else {
> +                tcg_out_movi (s, TCG_TYPE_I32, 0, arg2);
> +                tcg_out32 (s, XOR | SAB (arg1, 0, 0));
> +            }
> +        }
> +        else {
> +            tcg_out32 (s, XOR | SAB (arg1, 0, arg2));
> +        }
> +        tcg_out32 (s, CNTLZW | RS (0) | RA (0));
> +        tcg_out32 (s, (RLWINM
> +                       | RA (arg0)
> +                       | RS (0)
> +                       | SH (27)
> +                       | MB (5)
> +                       | ME (31)
> +                       )
> +            );
> +        return;
> +
> +    case TCG_COND_NE:
> +        if (const_arg2) {
> +            if ((uint16_t) arg2 == arg2) {
> +                tcg_out32 (s, XORI | RS (arg1) | RA (0) | arg2);
> +            }
> +            else {
> +                tcg_out_movi (s, TCG_TYPE_I32, 0, arg2);
> +                tcg_out32 (s, XOR | SAB (arg1, 0, 0));
> +            }
> +        }
> +        else {
> +            tcg_out32 (s, XOR | SAB (arg1, 0, arg2));
> +        }
> +
> +        tcg_out32 (s, ADDIC | RT (arg0) | RA (0) | 0xffff);
> +        tcg_out32 (s, SUBFE | TAB (arg0, arg0, 0));
> +        return;
> +
> +    case TCG_COND_LTU:
> +    case TCG_COND_LT:
> +        sh = 29;
> +        crop = 0;
> +        break;
> +
> +    case TCG_COND_GEU:
> +    case TCG_COND_GE:
> +        sh = 31;
> +        crop = CRNOR | BT (7, CR_EQ) | BA (7, CR_LT) | BB (7, CR_LT);
> +        break;
> +
> +    case TCG_COND_LEU:
> +    case TCG_COND_LE:
> +        sh = 31;
> +        crop = CRNOR | BT (7, CR_EQ) | BA (7, CR_GT) | BB (7, CR_GT);
> +        break;
> +
> +    case TCG_COND_GTU:
> +    case TCG_COND_GT:
> +        sh = 30;
> +        crop = 0;
> +        break;
> +
> +    default:
> +        tcg_abort ();
> +    }
> +
> +    tcg_out_cmp (s, cond, arg1, arg2, const_arg2, 7);
> +    tcg_out32 (s, MFCR | RT (0));
> +    if (crop) tcg_out32 (s, crop);
> +    tcg_out32 (s, (RLWINM
> +                   | RA (arg0)
> +                   | RS (0)
> +                   | SH (sh)
> +                   | MB (31)
> +                   | ME (31)
> +                   )
> +            );
> +}
> +
>  /* XXX: we implement it at the target level to avoid having to
>    handle cross basic blocks temporaries */
>  static void tcg_out_brcond2 (TCGContext *s, const TCGArg *args,
> @@ -1496,6 +1589,10 @@ static void tcg_out_op(TCGContext *s, int opc, const 
> TCGArg *args,
>         tcg_out32 (s, EXTSH | RS (args[1]) | RA (args[0]));
>         break;
>
> +    case INDEX_op_setcond_i32:
> +        tcg_out_setcond(s, args[3], args[0], args[1], args[2], 
> const_args[2]);
> +        break;
> +
>     default:
>         tcg_dump_ops (s, stderr);
>         tcg_abort ();
> @@ -1544,6 +1641,8 @@ static const TCGTargetOpDef ppc_op_defs[] = {
>
>     { INDEX_op_neg_i32, { "r", "r" } },
>
> +    { INDEX_op_setcond_i32, { "r", "r", "ri" } },
> +
>  #if TARGET_LONG_BITS == 32
>     { INDEX_op_qemu_ld8u, { "r", "L" } },
>     { INDEX_op_qemu_ld8s, { "r", "L" } },
>
> --
> mailto:address@hidden
>
>
>